The objective is to understand the neuroanatomical organization of areas of the nervous system responsible for control of food intake and body weight regulation. Although it has been known for some time that damage to certain areas of the hypothalamus can lead to obesity, the neuroanatomical organization of these areas, which include the ventromedial (VMN), arcuate (ARC) and dorsal premammillay (DP) nuclei, is not well understood. Recent biochemical evidence based on chemical stimulation and measurement of catecholamine levels has also implicated the paraventricular nucleus (PVN) and median eminence (ME). The present series of experiments are aimed at 1) elucidation of hypothalamic organization in normal rats and 2) determination of possible anatomical in normal rats and 2) determination of possible anatomical abnormalfties in the brains of genetically obese rats. Normal cytoarchitectonic features as well as nural connections of VMN, ARC, DP, DVN and ME will be studied. The techniques utilized will include Golgi, thionin, neurosecretory staining, autroradiography and horseradish peroxidase. In humans a relationship exists between obesity and certain diseases. Elucidation of the neuroanatomical pathways involved in the control of food intake and body weight regulation as well as demonstration of abnormalities in the brains of genetically obese animals will be of use in therapeutic approaches to obesity.